Although the work on catalase has had some unexpected problems in the previous year, it is hoped that further progress will go more smoothly and that a high resolution structure will be available in the next one, or at most two, years. The refinement of the various lactate dehydrogenase (LDH) structures is now progressing smoothly. Changes from real-space (Diamond) techniques to reciprocal space (Konnert and Hendrickson) techniques are to be considered. It is anticipated that refined structures of dogfish M4 apo LDH, of a dogfish M4 ternary complex, and of a pig H4 ternary complex will be available sometimes during the next two years. The structure of mouse LDH-X has been solved to 2.9 Angstrom units resolution and a model should be built within the next few months. Work is commencing on an apo glyceraldehyde-3-phosphate dehydrogenase structure, and it is likely that the necessary data will be collected within the next few months. A variety of other crystal structure determinations on dehydrogenases and nucleotide-binding proteins are in their initial exploratory stage. The comparison of active center geometries of different enzymes is to continue. BIBLIOGRAPHIC REFERENCES: Rossmann, M.G., P. Argos. 1977. The taxonomy of protein structure. J. Mol. Biol. 109:99-129. Tanaka, N. 1977. Representation of the faster rotation function in a polar coordinate system. Acta Crystallogr. A33:191-192.